Engineering Commons^™

A Use Of Theory Of Constraints Thinking Processes For Improvements In The Merged Beams Experiment At Oak Ridge National Laboratory., Bryan Richard Gross

Electronic Theses and Dissertations

Thinking exercises used in the Theory of Constraints (TOC) were used to find and remove constraints at the Merged Beams Experiment at Oak Ridge National Laboratory. The goal of this project was to significantly reduce the amount of time used to take a certain type of measurement during an experimental cycle. After the TOC exercises were used, a basic plan for change was discovered. Preliminary data were taken to establish a baseline of performance from which changes were made. Post-Modification was analyzed showing the project was a success.

The overlying reasoning for this exercise was to prove successfully that continuous …

Biological Conversion Of Hemicellulose Extract Into Value-Added Fuels And Chemicals, Sara Lynn Walton

Electronic Theses and Dissertations

The research presented in this thesis describes the fermentation of hemicellulose extracts to produce ethanol and lactic acid. Hardwood hemicellulose extracts made at a variety of conditions using the green liquor and hot water extraction processes were characterized and then fermented by Escherichia coli K011 and Bacillus coagulans MXL-9. Hemicellulose extracts were found to contain a dilute amount of xylo-oligosaccharides and acetic acid as the major components, and many minor components including other organic acids, lignin-derived phenolics, and sugar degradation products. In order to generate ethanol economically, the fermentation must produce at least a 4% ethanol solution, which requires a …

Exploring Earth-Building Technology For Liberia., Isaac Dompo Mayon

Electronic Theses and Dissertations

This paper discusses earth as a building material and the extent to which earth building technology has evolved over the years. In particular it addresses the adobe, compressed and rammed earth techniques of earth building as suitable techniques for Liberia consumption. In addition, the paper investigates the suitability of the Latosols soils of Liberia for earth building construction purposes using standardized earth building principles and requirements. A local Johnson City, Tennessee, earth sample found to have the same physical characteristics of the Latosols of Liberia was used to simulate Liberia soils to produce specimen blocks at different configurations of moisture …

Short-Term Failure Analysis Of Aluminum Conducting Composite Core Transmission Lines, Brian Burks

Electronic Theses and Dissertations

Recently the inefficiency and lack of capabilities of electric energy transmission have been put in the global spotlight; a transmission line design known as the Aluminum Conducting Composite Core Trapezoidal Wire (ACCC/TW^TM) attempts to eliminate the deficiencies. The ACCC core is comprised of a new hybrid composite material. The most probable causes of short-term damage to the ACCC core were investigated through a series of finite element models. It was found that excessive bending was the most likely cause of short-term damage to the core. During bending of the ACCC core, stresses are concentrated at the interface in …

Parametric Model Of Head Related Transfer Functions Based On Systematic Movements Of Poles And Zeros With Sound Location For Pole/Zero Models, Bahaa W. Al-Sheikh Hussein

Electronic Theses and Dissertations

Directional transfer functions (DTFs), the directional components of the Head Related Transfer Functions (HRTFs), are generally measured at finite locations in azimuth and elevation. Thus models are needed to synthesize DTFs at finer spatial resolution than the measured data to create complete virtual auditory displays. In this research, minimum-phase all-pole and all-zero models were used for modeling both human and cat DTFs. Real cepstrum analysis has been used to represent minimum phase HRTFs in the time domain. For the human DTFs, model orders were chosen to achieve specific objective error criteria published in previous studies that were based on subjective …

Development Of An Integrated Solar Heat Pipe System For Improving Building Energy Efficiency., Michael Vincent Albanese

Electronic Theses and Dissertations

The one dimensional heat transfer, thermal diode effect of heat pipes makes them ideal for passive solar applications. Gains in a heat pipe passive solar wall are not lost during cloud cover or periods of low irradiation. An experimental model was built to test the performance of a heat pipe passive solar wall in a laboratory setting. Experimental variations included varying fluid fill levels and the addition of insulation along the adiabatic section of the heat pipe. Filling the heat pipe to 120% volume of the evaporator section and insulating the adiabatic section achieved efficiencies of 85%. The average rate …

Lifetime Estimation Of Wireless Body Area Sensor Network For Patient Health Monitoring, Frank Agyei-Ntim

Electronic Theses and Dissertations

Wireless Body Area Sensor Networks (WBASN) is an emerging technology which utilizes wireless sensors to implement real-time wearable health monitoring of patients to enhance independent living. These sensors can be worn externally to monitor multiple bio-parameters (such as blood oxygen saturation (SpO2), blood pressure and heart activity) of multiple patients at a central location in the hospital.

In health monitoring, the loss of critical or emergency information is a serious issue so there is a concern for quality of service which needs to be addressed. It is important to have an estimate of the time the first node will fail …

Routing In The Dark: Pitch Black, Nathan S. Evans

Electronic Theses and Dissertations

In many networks, such as mobile ad-hoc networks and friend-to-friend overlay networks, direct communication between nodes is limited to specific neighbors. Friendto-friend “darknet” networks have been shown to commonly have a small-world topology; while short paths exist between any pair of nodes in small-world networks, it is non-trivial to determine such paths with a distributed algorithm. Recently, Clarke and Sandberg proposed the first decentralized routing algorithm that achieves efficient routing in such small-world networks.

Herein this thesis we discuss the first independent security analysis of Clarke and Sandberg’s routing algorithm. We show that a relatively weak participating adversary can render …

Multifunctional Nanocomposites For High Damping Performance, Lee Algozzini

Electronic Theses and Dissertations

Composite structures for aerospace and wind turbine applications are subjected to high acoustic and vibrational loading and exhibit very high amplitude displacements and thus premature failure. Materials with high damping or absorbing properties are crucially important to extend the life of structures. Traditional damping treatments are based on the combinations of viscoelastic, elastomeric, magnetic, and piezoelectric materials. In this work, the use of carbon nanofibers (CNFs) in the form of interconnected self-supportive paper as reinforcement can significantly improve damping performance. The interfacial friction is the primary source of energy dissipation in CNF paper based nanocomposites. The approach entailed making CNF …

Thermo-Mechanical Characterization Of High-Temperature Shape Memory Ni-Ti-Pd Wires, Matthew Fox

Electronic Theses and Dissertations

Actuator applications of shape memory alloys have typically been limited by their phase transformation temperatures to around 100 degrees C. However, recently with a focus on aerospace and turbomachinery applications there have been successful efforts to increase the phase transformation temperatures. Several of these alloy development efforts have involved ternary and quaternary elemental additions (e.g., Pt, Pd, etc.) to binary NiTi alloys. Experimentally assessing the effects of varying composition and thermo-mechanical processing parameters can be cost intensive, especially when expensive, high-purity elemental additions are involved. Thus, in order to save on development costs there is value in establishing a methodology …

Magnetically Deflectable Mems Actuators For Optical Sensing Applications, Matthew Montgomery

Electronic Theses and Dissertations

In this work, new small deflection magnetic actuators have been proposed, designed, and tested for applications in Surface Enhanced Raman Scattering optical sensors. Despite the fact that SERS sensors have been shown to increase Raman over ten orders of magnitude for molecular detection, several technological challenges have prevented the design of practical sensors, such as making SERS sensors that can efficiently detect a wide variety of molecules. Since the optimum signal-to-noise in SERS occurs at different excitation wavelengths for different molecules, individual metal nanostructures need to be designed and fabricated for each independent chemical species. One possible solution to this …

Femtosecond Laser Written Volumetric Diffractive Optical Elements And Their Applications, Jiyeon Choi

Electronic Theses and Dissertations

Since the first demonstration of femtosecond laser written waveguides in 1996, femtosecond laser direct writing (FLDW) has been providing a versatile means to fabricate embedded 3-D microstructures in transparent materials. The key mechanisms are nonlinear absorption processes that occur when a laser beam is tightly focused into a material and the intensity of the focused beam reaches the range creating enough free electrons to induce structural modification. One of the most useful features that can be exploited in fabricating photonic structures is the refractive index change which results from the localized energy deposition. The laser processing system for FLDW can …

Contextualizing Observational Data For Modeling Human Performance, Viet Trinh

Electronic Theses and Dissertations

This research focuses on the ability to contextualize observed human behaviors in efforts to automate the process of tactical human performance modeling through learning from observations. This effort to contextualize human behavior is aimed at minimizing the role and involvement of the knowledge engineers required in building intelligent Context-based Reasoning (CxBR) agents. More specifically, the goal is to automatically discover the context in which a human actor is situated when performing a mission to facilitate the learning of such CxBR models. This research is derived from the contextualization problem left behind in Fernlund's research on using the Genetic Context Learner …

Visual Inspection Of Railroad Tracks, Pavel Babenko

Electronic Theses and Dissertations

In this dissertation, we have developed computer vision methods for measurement of rail gauge, and reliable identification and localization of structural defects in railroad tracks. The rail gauge is the distance between the innermost sides of the two parallel steel rails. We have developed two methods for evaluation of rail gauge. These methods were designed for different hardware setups: the first method works with two pairs of unaligned video cameras while the second method works with depth maps generated by paired laser range scanners. We have also developed a method for detection of rail defects such as damaged or missed …

Detecting Malicious Software By Dynamicexecution, Jianyong Dai

Electronic Theses and Dissertations

Traditional way to detect malicious software is based on signature matching. However, signature matching only detects known malicious software. In order to detect unknown malicious software, it is necessary to analyze the software for its impact on the system when the software is executed. In one approach, the software code can be statically analyzed for any malicious patterns. Another approach is to execute the program and determine the nature of the program dynamically. Since the execution of malicious code may have negative impact on the system, the code must be executed in a controlled environment. For that purpose, we have …

An Architecture For High-Performance Privacy-Preserving And Distributed Data Mining, James Secretan

Electronic Theses and Dissertations

This dissertation discusses the development of an architecture and associated techniques to support Privacy Preserving and Distributed Data Mining. The field of Distributed Data Mining (DDM) attempts to solve the challenges inherent in coordinating data mining tasks with databases that are geographically distributed, through the application of parallel algorithms and grid computing concepts. The closely related field of Privacy Preserving Data Mining (PPDM) adds the dimension of privacy to the problem, trying to find ways that organizations can collaborate to mine their databases collectively, while at the same time preserving the privacy of their records. Developing data mining algorithms for …

Alliances In Graphs: Parameterized Algorithms And On Partitioning Series-Parallel Graphs, Rosa Enciso

Electronic Theses and Dissertations

Alliances are used to denote agreements between members of a group with similar interests. Alliances can occur between nations, biological sequences, business cartels, and other entities. The notion of alliances in graphs was first introduced by Kristiansen, Hedetniemi, and Hedetniemi in . A defensive alliance in a graph G = (V, E) is a non empty set S ⊆ V where, for all x ∈ S, |N[x] ∩ S| ≥ |N[x] − S|. Consequently, every vertex that is a member of a defensive alliance has at least as many vertices defending it as there are vertices attacking it. Alliances can …

Design And Analysis Of Effective Routing And Channel Scheduling For Wavelength Division Multiplexing Optical Networks, Xingbo Gao

Electronic Theses and Dissertations

Optical networking, employing wavelength division multiplexing (WDM), is seen as the technology of the future for the Internet. This dissertation investigates several important problems affecting optical circuit switching (OCS) and optical burst switching (OBS) networks. Novel algorithms and new approaches to improve the performance of these networks through effective routing and channel scheduling are presented. Extensive simulations and analytical modeling have both been used to evaluate the effectiveness of the proposed algorithms in achieving lower blocking probability, better fairness as well as faster switching. The simulation tests were performed over a variety of optical network topologies including the ring and …

Concept Learning By Example Decomposition, Sameer Joshi

Electronic Theses and Dissertations

For efficient understanding and prediction in natural systems, even in artificially closed ones, we usually need to consider a number of factors that may combine in simple or complex ways. Additionally, many modern scientific disciplines face increasingly large datasets from which to extract knowledge (for example, genomics). Thus to learn all but the most trivial regularities in the natural world, we rely on different ways of simplifying the learning problem. One simplifying technique that is highly pervasive in nature is to break down a large learning problem into smaller ones; to learn the smaller, more manageable problems; and then to …

Connectionless Approach: A Localized Scheme To Mobile Ad Hoc Networks, Yao Ho

Electronic Theses and Dissertations

According to a Gartner Group (www.gartner.com) report in September 2008, the worldwide telecommunications market is on pace to reach $2 trillion in 2008. Gartner predicts that by 2012, the ratio of mobile to fixed connections will exceed 4-to-1. The North American mobile data market grew to 141.1 million connections in 2007, with a compound annual growth rate of 41.7 percent. It is believed that a large portion will be ad hoc and multi-hop connections, which will open many opportunities for Mobile Ad hoc NETwork (MANET) applications and Wireless Mesh Network (WMN) applications. A MANET is a self-organizing multi-hop wireless network …

Modeling Scenes And Human Activities In Videos, Arslan Basharat

Electronic Theses and Dissertations

In this dissertation, we address the problem of understanding human activities in videos by developing a two-pronged approach: coarse level modeling of scene activities and fine level modeling of individual activities. At the coarse level, where the resolution of the video is low, we rely on person tracks. At the fine level, richer features are available to identify different parts of the human body, therefore we rely on the body joint tracks. There are three main goals of this dissertation: (1) identify unusual activities at the coarse level, (2) recognize different activities at the fine level, and (3) predict the …

Learning Techniques For Information Retrieval And Mining In High-Dimensional Databases, Hao Cheng

Electronic Theses and Dissertations

The main focus of my research is to design effective learning techniques for information retrieval and mining in high-dimensional databases. There are two main aspects in the retrieval and mining research: accuracy and efficiency. The accuracy problem is how to return results which can better match the ground truth, and the efficiency problem is how to evaluate users' requests and execute learning algorithms as fast as possible. However, these problems are non-trivial because of the complexity of the high-level semantic concepts, the heterogeneous natures of the feature space, the high dimensionality of data representations and the size of the databases. …

Efficient Techniques For Relevance Feedback Processing In Content-Based Image Retrieval, Danzhou Liu

Electronic Theses and Dissertations

In content-based image retrieval (CBIR) systems, there are two general types of search: target search and category search. Unlike queries in traditional database systems, users in most cases cannot specify an ideal query to retrieve the desired results for either target search or category search in multimedia database systems, and have to rely on iterative feedback to refine their query. Efficient evaluation of such iterative queries can be a challenge, especially when the multimedia database contains a large number of entries, and the search needs many iterations, and when the underlying distance measure is computationally expensive. The overall processing costs, …

Geometric Invariance In The Analysis Of Human Motion In Video Data, Yuping Shen

Electronic Theses and Dissertations

Human motion analysis is one of the major problems in computer vision research. It deals with the study of the motion of human body in video data from different aspects, ranging from the tracking of body parts and reconstruction of 3D human body configuration, to higher level of interpretation of human action and activities in image sequences. When human motion is observed through video camera, it is perspectively distorted and may appear totally different from different viewpoints. Therefore it is highly challenging to establish correct relationships between human motions across video sequences with different camera settings. In this work, we …

Scheduling And Resource Management For Complex Systems: From Large-Scale Distributed Systems To Very Large Sensor Networks, Chen Yu

Electronic Theses and Dissertations

In this dissertation, we focus on multiple levels of optimized resource management techniques. We first consider a classic resource management problem, namely the scheduling of data-intensive applications. We define the Divisible Load Scheduling (DLS) problem, outline the system model based on the assumption that data staging and all communication with the sites can be done in parallel, and introduce a set of optimal divisible load scheduling algorithms and the related fault-tolerant coordination algorithm. The DLS algorithms introduced in this dissertation exploit parallel communication, consider realistic scenarios regarding the time when heterogeneous computing systems are available, and generate optimal schedules. Performance …

Validation Of Quickscat Radiometer (Qrad) Microwave Brightness Temperture Measurments, Rafik Hanna

Electronic Theses and Dissertations

After the launch of NASA's SeaWinds scatterometer in 1999, a radiometer function was implemented in the Science Ground Data Processing Systems to allow the measurement of the earth's microwave brightness temperature. This dissertation presents results of a comprehensive validation to assess the quality of QRad brightness temperature measurements using near-simultaneous ocean Tb comparisons between the SeaWinds on QuikSCAT (QRad) and WindSat polarimetric radiometer on Coriolis. WindSat was selected because it is a well calibrated radiometer that has many suitable collocations with QuikSCAT; and it has a 10.7 GHz channel, which is close to QRad frequency of 13.4 GHz. Brightness temperature …

Embedded Magnetics For Power System On Chip (Psoc), Jian Lu

Electronic Theses and Dissertations

A novel concept of on-chip bondwire inductors and transformers with ferrite epoxy glob coating is proposed, offering a cost effective approach to realize power systems on chip (PSoC) or System-in-Package (PSiP). The concept has been investigated both experimentally and with finite element modeling. Improvement in total inductance is demonstrated for multi-turn bondwire inductors over single bondwire inductors. The inductance and Q factor can be further boosted with coupled multi-turn inductor concept. Transformer parameters including self- and mutual inductance, and coupling factors are extracted from both modeled and measured S-parameters. More importantly, the bondwire magnetic components can be easily integrated into …

Learning Semantic Features For Visual Recognition, Jingen Liu

Electronic Theses and Dissertations

Visual recognition (e.g., object, scene and action recognition) is an active area of research in computer vision due to its increasing number of real-world applications such as video (image) indexing and search, intelligent surveillance, human-machine interaction, robot navigation, etc. Effective modeling of the objects, scenes and actions is critical for visual recognition. Recently, bag of visual words (BoVW) representation, in which the image patches or video cuboids are quantized into visual words (i.e., mid-level features) based on their appearance similarity using clustering, has been widely and successfully explored. The advantages of this representation are: no explicit detection of objects or …

Study Of Gate Oxide Breakdown And Hot Electron Effect On Cmos Circuit Performances, Jun Ma

Electronic Theses and Dissertations

In the modern semiconductor world, there is a significant scaling of the transistor dimensions--The transistor gate length and the gate oxide thickness drop down to only several nanometers. Today the semiconductor industry is already dominated by submicron devices and other material devices for the high transistor density and performance enhancement. In this case, the semiconductor reliability issues are the most important thing for commercialization. The major reliability issues caused by voltage are hot carrier effects (HCs) and gate oxide breakdown (BD) effects. These issues are recently more important to industry, due to the small size and high lateral field in …

Phase Shaping In The Infrared By Planar Quasi-Periodic Surfaces Comprised Of Sub-Wavelength Elements, James Ginn

Electronic Theses and Dissertations

Reflectarrays are passive quasi-periodic sub-wavelength antenna arrays designed for discrete reflected phase manipulation at each individual antenna element making up the array. By spatially varying the phase response of the antenna array, reflectarrays allow a planar surface to impress a non-planar phasefront upon re-radiation. Such devices have become commonplace at radio frequencies. In this dissertation, they are demonstrated in the infrared for the first time--at frequencies as high as 194 THz. Relevant aspects of computational electromagnetic modeling are explored, to yield design procedures optimized for these high frequencies. Modeling is also utilized to demonstrate the phase response of a generalized …